This is a limitation of current RANGE implementation. It will be fixed when MDEV-9727 is also fixed.

While MDEV-9727 will fix this, as UNBOUNDED won't look at the type or the value, maybe this could still be done.

I do not want to introduce a hack to only allow RANGE type frames, regardless of data type, if UNBOUNDED PRECEDING & UNBOUNDED FOLLOWING is present on the respective ends of the window frame. This would create queries like this that work:

select symbol, first_value(price) over w as first, last_value(price) over w as last

from ticks

window w as (partition by symbol order by date_2 range between UNBOUNDED PRECEDING and UNBOUNDED FOLLOWING)

and queries like this that do not work:

select symbol, first_value(price) over w as first, last_value(price) over w as last

from ticks

window w as (partition by symbol order by date_2 range between UNBOUNDED PRECEDING and CURRENT ROW)

This would set confusing expectations for users and we'd also have a very peculiar documentation problem that needs to always be maintained as long as that version is supported.
Documentation would have to read something like:
"For RANGE type frames, starting with MariaDB 10.9, it works for all data types when the window bounds are UNBOUNDED PRECEDING and UNBOUNDED FOLLOWING".

We should just get MDEV-9727 implemented instead, not waste time with hacks.

Ok.